1. Field of the Invention
The invention relates in general to a facial expression recognition apparatus and a facial expression recognition method thereof, and more particularly to a facial expression recognition apparatus having the low operation loading, and a facial expression recognition method thereof.
2. Description of the Related Art
In the life, people often express the inward emotion through the facial expression. The emotion expressing region mainly includes the mouth, the eyes, the eyebrows, the jowls and the like. When a person is expressing his inward emotion, only the local feature on the face is changed (e.g., the corners of the mouth are turned up) such that the emotion can be expressed. In the technology changing with each passing day, people further hope to apply the facial expression recognition to the electronic device to significantly enhance the convenience of application.
The smiling face detection is one of the important items of the facial expression detection, and its processing methods may be divided into the face feature detection technology and the classifier technology. In the conventional face feature detection technology, fixed frames corresponding to the eyes, the nose and the mouth are often set on the face region, and then the face feature positions are calculated by way of statistical comparison, as disclosed in Taiwan Patent Nos. 00445434; TW226589B and U.S. Pat. No. 6,526,161. In addition, regarding the classifier technology, U.S. Pat. No. 6,430,307 disclosed a feature extraction system and a face image recognition system, in which the original samples and the newly added samples are put into the PCA so that the orthonormal base is calculated, and then the comparison is made to determine whether a match occurs or not.
However, the conventional facial expression detection technology has the great operation loading, and cannot be easily used in an embedded platform (e.g., a digital camera). In addition, the conventional facial expression detection technology tends to be influenced by the light source. When the brightness is nonuniform, the correctness of the facial expression recognition result is directly influenced.